#include <bits/stdc++.h>

#define endl '\n'

using namespace std;

typedef long long LL;

int main()
{
    ios::sync_with_stdio(false), cin.tie(0), cout.tie(0);
	
	LL a, b, n;
	
	cin >> a >> b >> n;
	
	LL week = 5ll * a + 2ll * b;
	
	LL t = n / week * 7;
	n %= week;
	
	for (int i = 1; i <= 7; i ++ )
	{
		if (i <= 5 && i >= 1)
		{
			n -= a;
		}
		else n -= b;
		
		if (n <= 0)
		{
			t += i;
			break;
		}
	}
	
	cout << t << endl;
	
    return 0;
}